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C. S: DEMARE$T.

AMPLIFIER FOR BIN-SING CURRENTS APPLlCfflmN FILED APR, 1mm.

3 ,3 :3,-%%2D Patented Nov. 18, 1919.

2 SHEETSSHEET 2.

l. I N I N 8 mfr-w IN V EN TOR.

A TTO-RNEY PATENT QTFFTQE;

CHARLES S. DF'IVIAR-EST, 0F BROOKLYN, NEW YORK, ASSIGNOB TO AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

AMPLIFIER FOR RINGING-CURBENTS.

Specification of Letters Patent.

Patented Nov. 18, 1919..

T 0 all whom it may concern:

Be it known that 1, CHARLES S. DEM- AREST, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Amplifiers for Ringing-Currents, of which the following is a specification.

This invention relates to transmission lines in which are included repeater elements, and more particularly to a means for transmit ting ringing current over such lines.

lt is one of the objects of the invention to provide means for transmitting amplified ringing current through a repeater station included in a transmission line. A further object is to provide means whereby during the ringing operation all the amplified energy is transmitted to the outgoing line. Other and further objects of the invention will be clear from the detailed description to be given later The purposes of this invention are accomplished by so modifying a two-way tworepeater circuit that it will function during the transmission of ringing current as a one way repeater circuit for amplifying ringing current. Switching means responsive to ringing current are So arranged that upon their actuation, the output circuit of the amplifier for repeating in the direction in which the ringing current is transmitted, is disconnected from the usual three-winding transformer of the other amplifier, and is connected to the outgoing line through an auxiliary circuit, the other amplifier being at the same time disconnected from the outgoing line so that it is inoperative. The ringing current is then transmitted from the. incoming line through the amplifier directly to the outgoing line and no energy is wasted inthe balancing artificial lines.

This invention may now be more fully understood from the following detailed description taken in connection with the accompanying drawings, in the Figures 1 and 2 of which when taken together is illustrated a preferred form of the circuit ar rangement of my invention. The characters L, and L represent incoming and outgoing transmission lines associated with a two- 'way two-element repeater. which is diaknown type, such as the mechanical repeater, may be employed. Associated with the repeater elements R and R, are the artificial lines N and N which are adapted to balance the sections L and L respectively, or

of the transmission line. Bridged from the mid-points of the input windings of the repeaters R and R are thei'elays 2 and 5, respectively. These relays are adapted to be energized by the ringing current coming in over the sections L and L of the trans mission line. Under the control of these relays are additional normally energized relays 10 and 11. The dencrgization of relay 10 serves to operate relays 3 and 6. energization of relay 11 serves to operate relays 4t and 1. The operation of relays 3 and st serves to open the outgoing talking circuits of the repeaters and allows the amplified ringing current to be transmitted directly from the repeaters to the transformer 7. Transformer 7 is designed to be highly eflicient for the particular frequency of the ringing current employed, and which in practice mav be in the neighborhood of 183 lines N and N respectively, so that none of the energy of the incoming ringing current will be wasted thereover.

Further details of the invention will now be clear from the following description of its operation: The ringing current in com 5 ing over the line L will pass through the windings 22 and 23 and over conductors 26 and 27, and thence through the right-hand winding of transformer 32. A portion of this ringing current will also pass through the winding of the relay 2 and cause it to 0p crate. The operation of relay 2 causes it to pull up its armature and break the following normally closed circuit through re-' lay 10: from ground and battery, Winding of relay 10, conductor 31. armature of relay 2 to groimd. This will denergize relav 10 and allow" its armature to falloii' and rilose the following circuit: from ground and battery, winding "of relay 3, concluctoi i 18.; con: lit

The de- 70 By these means the 85 tacts of relay 10, conductor 20, and Wind ing of relay (5 to ground. The closing of this last mentioned circuit operates relays 3 and 6. The operation of relay 3 opens the talking circu t of the repeater R and allows the repeated ringing current to pass over conductors 14 and 15, instead of over the talking conductors 36 and 37. This repeated ringing current Will then pass over conductors 16 and 17 through one Winding of the step-up transformer 7. An induced amplified ringing current will then be transmitted from the other Winding of transformer 7 over conductors 8 and 9 to the armatures of relay 6. As has been formerly pointed out, the relay (-3 was energized, and

accordingly this ringing current Will be transmitted from the armatures of relay 6 over the line section L Ringing current in coming over section L, of the transmission line Will be transmitted through the windings 24 and 25 and over the conductors 28 and 29 and the Winding of nected from the repeater R and amplified ringing current Will pass over the conductors 34 and 35 instead of over the talking conductors 38 and 39. This repeated ringing current will then pass over conductors 16 and 17 and through one Winding of the transformer 7, and induced amplified ringing current will then be transmitted from the other Winding over conductors 8 and 9 to the armatures of relay 1. As this relay has already been energized, it will be seen that ringing current will be transmitted over the armatures of relay 1, and over the section L of the transmission line.

It Will be obvious that the-general principlcs herein disclosed play "be embodied in many organizations other than those illus trated Without departing from the spirit of the invention, as defined in thefollowing claims.

I claim:

1. In a transmission system comprising two line sections, a two-Way two-repeater organization interconnecting said line sections for the transmission of talking currents, said repeater organization including artificial lines for balancing said line sections and two-repeater elements, each re peatcr elementhaving its input circuit asso- 'DldEQCl with one of said tin sections, and

hai ing its output circuit associated With the other line section and thelcorresponding artificial line in such manner that substantially half of the output energy is transmitted to the artificial line, and' means di rectly responsive to ringingcurrent trans' mitted over one line section to disconnect the output circuit of the repeater element associated with said section from the other line section and artificial line, and connecting the output circuit to the outgoing line only.

2min a transmission system comprising two line sections, a two-Way two-repeater organization interconnecting said line seetions'for the transmission of talking cur rents, said repeater organization including artificial lines for balancing said ,line sections and two-repeater elements each repeater element l'iaving its input circuit associated with one of said line sections, and having its output circuit associated with the other-line section and the corresponding artificial line in such manner that substantially half of the output energy is trans- J mitted to the artificial line, and means directly responsive to ringing current transmitted over one line section to disconnect the output circuit'of the repeater element associated with said section from the other line section and artificial line, and connecting the output circuit to the outgoing line only, whereby ringing current transmitted over one line section is amplified by the repeater element and directly transmitted to the other line section.

3; In a transmission system comprising two line sections, a two-Way two-repeater organization interconnecting said line sections for the transmission of talkin currents, said repeater organization incliiding artificial lines for balancing said line sections and two-repeater elements each repeater elcment having its input circuit associated with one of said lin'e sections, and having its output circuit associated with the other line section and the corresponding artificial line in such manner that substantially half of the output energy is transmitted to the artificial line, an auxiliary circuit to which either line section may be connected, and means for connecting the output of the repeater element associated with one of said line sections to said auxiliary circuit and for simultaneously connecting said auxiliary circuit to the other line section.

4. In a transmission system comprising two line sections, a tivo-way two-repeater organization interconnecting said line sections for the transn'lission of talking currents, said repeat-er organization including artil'cial lines for balancing said ine sections and two-repeater elements, each re peater element having its input circuit associated with one of said line sections and havjug its output circuit associated With the lessees other line section and the COIIQSPOIKliilg artificial line in such manner that substantiall half of the output energy is transmitted to the artificial line, means directly responsive to ringing current transmitted over one line section to disconnect the output circuit of the repeater element associated with said section from the other line sect-ion and artificial line and connecting the output circuit to the outgoing line only, and means controlled by said directly responsive means to disconnect the artificial line from the line section over which the ringing current is transmitted.

5. In a transmission system comprising twoline sections, a two-Way two-repeater organization interconnecting said line sec. tions for the transmission of talking currents, said repeater organization including artificial lines for balancing said line section and two-repeater elements, each repeater element having its input circuit associated with one of said line sections and having its output circuit associated with the other line se tion and the corresponding artificial line in such manner that substantially half of the output energy is transmitted to the artificial line, and means responsive to the ringing current transmitted over one line section to disconnect the artificial line associated with said line section April, 1918.

so that none of the ringii current is diverted through the itfiifif linei.

o. In a transmihgion s two line sections, a two-way two-rt organization interconnectii'ig d line sections for the transmission of taiiiing currents, said repeater organization including artificial lines for bz-ilancing said iine sections and two-repeater elements, each re peater element having its input circuit asso ciated with one of said line sections, and having its output circuit associated with the tem con'iprising other line section and the corresponding artificial line in such manner that substantially half of the output energy is transmitted to the artificial line, an auxiliary circuit to which either line section may he connectet, said auxiliary circuit including a trans former adapted to be highiy eiiic-ient for the transmission of currents having a frequency of the order of the currents employed for ringing purposes, and mm 'or coi'inecting the output oi the repeater element associated. with one of said line sections to said illlXli iary circuit and for simultaneously connec ing said auxiliary circuit to the other line section.

In testimony whereof I have signed my name to this specification this eighth day of CHARLES S. DEMAREST. 

